Introduction to z/OS Basics
Chapter 8: Designing and developing
applications for z/OS
© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Chapter objectives
Be able to:
Describe the roles of the
application designer and application
programmer.

 List the phases of the application
development life cycle.
 Briefly describe the process for
testing a new application on z/OS.
 Describe the advantages and
disadvantages of using batch versus
online for an application.
 List three reasons for using z/OS
as the host for a new application.
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© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Key terms in this chapter
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 application
 executable
 architecture
 infrastructure
 database
 platform
 design
 requirement
 develop
 transaction
 enablement
 unit test
© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
What is an application?
 An application
– A piece of software that will satisfy certain specific
requirements or resolve certain problems
– The solution can reside on any platform or combination of
platforms
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© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Who designs applications for the mainframe?
Application designer:
 Determines the best programming solution for an important
business requirement.
 Understands:
– Business objectives of the company
– Other roles in the mainframe IT organization
– Company’s hardware and software.
 Has a global view of the entire project.
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© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Who writes applications for the mainframe?
Application programmer:
 Builds, tests, and delivers the applications that run on the
mainframe for end users
 Works from the application designer’s specifications
 Uses a variety of tools
Application programming involves many iterations of:
 Code changes and compiles
 Application builds
 Unit testing.
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© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Where applications reside
In te rn e t
E n te rp ris e N e tw o rk
C e n tra l S ite
B ro w s e r
W eb
S e rve r
A p p l.
S e rve r
e -b u s in e s s
B ro w s e r
B ro w s e r
W eb
S e rve r
A p p l.
S e rve r
B u s in e s s S ys te m s
D a ta b a s e s
e -b u s in e s s
w ith L e ga c y S y s te m s
B ro w s e r
S e rve r
C lie n t-S e rve r
B u s in e s s
S y s te m s
A p p lic a tio n s
P e rs o n a l
C o m p u te r
G U I F ro n t-E n d
P e rs o n a l
C o m p u te r
B u s in e s s
S ys te m s
F ro n t E n d
Te rm in a l
P ro c e s s in g
"D u m b " Te rm in a l
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© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Application development lifecycle
G a th e r
re q u ire m e n ts
A n a ly s is
C o d e & te s t
8
D e s ig n
U s e r, S y s te m
Go
te s ts
p ro d u c tio n
M a in te n a n c e
© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Gathering requirements for the design
 Requirements:
– Assess what needs to be accomplished
• Based on projects constraints
• Always keep in mind the end result
• Conduct interviews with users and
stakeholders
• Verify our assumptions
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© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Types of requirements
 Accessibility
 Usability
 Client
 Frequency of data backup
 Interoperability
 Distributed
 Recoverability
 Portability
 Serviceability
 Secure centralized
controllable capacity
 Availability
 Connectivity
 Performance
 Resource can be
monitored, controlled,
managed, and
administered
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 Web services
 Changeability
 Inter-communicable
 Preventing failure and
fault analysis
© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Design phase
U s e rs
C o n stra in ts
R e q u ire m e n ts
B u sin e ss
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Te ch n ica l
V e rify
A n a lysis
R e vis e
V e rify
D e sig n
D e sig n
d o cu m e n ts
R e vise
© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Design decisions – based on requirements
 Batch versus online
 Database, tape, flat file, etc.
 COBOL, PL/I, JAVA, Assembler
 z/OS, Unix, Linux, Windows
 Capacity of server
 Server type
 Develop or purchase package or both
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© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Development phase
D e s ig n
d o c u m e n ts
C o d in g
Te stin g
Te ste d
p ro g ra m s
R e vis e
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© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Developing an application for the mainframe
 Programmer uses as input the specifications of
the designer
 Usually follows this process:
– Code a module.
– Test a module for functionality.
– Make corrections to the module.
– Repeat from step 2 until successful.
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© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Programming tools for the mainframe
• Editor
• TSO or ISPF-based
• Repository for source code
• PDS, SCLM or some other repository
• Job monitoring and viewing software
• SDSF or equivalent product
– Debugging tools
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© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Debugging a program on the mainframe
– Log on to TSO
– Enter ISPF – check out source code
– Edit source and make modifications
– Submit compile JCL to verify syntax
– Switch to SDSF to view job status
– View job output in SDSF – check for errors
– Correct errors
– Repeat from “Submit” until errors are corrected
– Save source code in repository
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© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Interactive Development Environment (IDE)
 IDEs accelerate development
process
– Edit source on work station
– Run compiles off-platform
– Perform remote debugging
– Useful for “hybrid” applications
•
•
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Host-based COBOL with
CICS, IMS, and Web
browser-like interface
Provides unified development
environment to build OLTP in
HLL and HTML front-end
interface
90
80
70
60
East
West
North
50
40
30
20
10
0
1st Qtr
2nd Qtr 3rd Qtr
4th Qtr
© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Test phase
U ser
Te s te d
p ro g ra m s
V a lid a te
Te s t
P e r fo r m a n c e
re s u lts
F in a l
te s te d
p ro g ra m s
In te g ra tio n
te s ts
Te s t d a ta
P ro d
d a ta
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O th e r
s ys te m s
© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Test phases (continued)
 Many levels of testing
– User testing for functionality, acceptance
– Performance (stress) testing
– Integration testing (with other systems)
 Validate the testing results
 Final step before going production
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© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Production phase
F in a l
te s te d
p ro g ra m s
20
P ro m o te
To
p ro d u c tio n
P ro d u c tio n
R e p o s ito ry
© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Go production
 Document:
– Operational procedures
– Training manuals (users, administrators, etc.)
 Promote application to production status
– Implement change control process
 Hand over to operations
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© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Maintenance phase
 Ongoing day-to-day changes/enhancements
 Responsibility for maintenance may change to
another group or stay with developers
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© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Maintaining and enhancing existing systems
 Maintenance and enhancement is a primary role of
HLL programmers on the mainframe
 Large corporations continue to use COBOL and
other traditional languages for new development:
– Existing applications are in HLLs such as COBOL and
PL/I
– New applications are in JAVA, COBOL and PL/I COBOL,
PL/I continue to be enhanced to exploit new technologies
and new data formats
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© 2006 IBM Corporation
Chapter 08 Designing z/OS Apps.
Summary
 Designing and developing an application for the
mainframe is similar to other platforms, but some of the
questions and conclusions are different.
 Life cycle of designing and developing an application to
run on z/OS includes phases of:
– Requirements gathering and analysis
– Design
– Development
– Test and debugging
– Production
– Maintenance
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© 2006 IBM Corporation
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